The invention relates to secateurs that are adjustable to provide a precise alignment between a cutting blade edge and an anvil surface. The production of such secateurs involves the problem of alignment between the cutting edge and anvil surface. When the secateurs are closed, the cutting edge of the cutting blade is intended to rest, over its entire length, on the anvil surface such that no light gap can be seen therebetween. This condition cannot easily be satisfied in production on account of tolerances, with the result that adjustments are usually necessary in order to adjust the cutting edge parallel to the anvil surface. It has been found in practice that, in production, there may be an angle of 1xc2x0 between the cutting edge and anvil surface to both sides of the zero line.
Adjustment by bending the secateur parts is difficult and requires specialist experience and is also very time-consuming.
In order to simplify the adjustment, it is known for the anvil (or the cutting blade) to be rendered adjustable in relation to the bearing secateur limb via a guide, the two parts being fixed by screw/nut bracing.
U.S. Pat. No. 3,372,478 discloses such an arrangement in which the anvil is provided with a curved bearing surface which rests on a correspondingly curved bearing surface of the secateur limb which bears the anvil. The anvil is fastened on the secateur limb by a clamping screw.
In secateurs according to U.S. Pat. No. 2,528,815, the anvil can be displaced in a guide and is supported against pin stops. Firm clamping takes place via a clamping screw, which projects in through an adjustment-permitting slot.
According to EP-A-0 527 358, the guide adjustment device comprises two slots which are positioned with opposite directions of inclination in relation to the cutting edge and have anvil sleeves passing through them, it being possible for screws to be screwed into said anvil sleeves, the anvil being clamped firmly in the process.
U.S. Pat. No. 2,821,018 discloses secateurs of the generic type in which a removable anvil can be secured on the secateur limb in an adjustable manner by way of two screws, it being possible for the adjustment to take place such that the cutting edge of the cutting blade produces linear contact with the anvil throughout when the limbs are closed. As with the other known secateurs described above, the securing operation also takes place in this case with a friction clip.
All these adjustment devices allow precise light-gap-free adjustment between the anvil and cutting edge. However, it is not always ensured that the adjustment position is reliably maintained. If the screw is not screwed firmly enough into the lock nut or loosens or, for some other reasons, the friction fit provided by the bracing between the anvil and secateur limb is not sufficient in order to withstand the forces occurring, then angular adjustment cannot be ruled out, which results in a wedge-shaped light gap in one direction or the other.
Such secateurs are subjected to a wide variety of stressing in dependence on where, for example, a branch which is to be cut, comes to rest on the anvil and whether said branch runs perpendicularly to the cutting edge or obliquely thereto while the cut is executed. For this reason, stressing which results in a sliding movement may occur.
The object set forth is achieved by providing a screw in an arcuate slot to permit adjustment of a relationship between and edge of the cutting blade and the anvil. The screw has an annular cutting edge that can provide a clamping mechanism in conjunction with the anvil. Since the nut digs into the anvil, which generally consists of aluminum, by way of its annular cutting edge, this achieves a form-fitting groove/tongue connection which rules out mutual adjustment even under extremely high stressing.
The set object is achieved by the features specified in the defining part of patent claim 1. Since the nut digs into the anvil, which generally consists of aluminum, by way of its annular cutting edge, this achieves a form-fitting groove/tongue connection which rules out mutual adjustment even under extremely high stressing.
The possible adjustment between the anvil and secateur blades can take place in various ways, for example via two slots which are positioned with opposite directions of inclination in relation to the cutting edge and have the clamping screws passing through them, as is the case for example, in EP-A-0 527 358.
According to the preferred embodiment of the invention, two standard screws are provided, of which one acts through a bushing designed as a pivot bearing (small amount of play, no loading on the thread) and the other acts in a circle-arc slot which is concentric with said bushing and can automatically be secured with a form fit, by way of its cutting nut, at a location determined by the adjustment in closing of the secateurs. According to the preferred embodiment, the arcuate slot is provided in the anvil, which consists of aluminum, while the cutting nut is inserted in a rotationally fixed manner in the secateur limb, which consists of hardened steel.
Accordingly, using the principle of the invention, different versions which all have in common the idea of an annular cutting edge cutting or pressing in, and are all to be afforded protection, are conceivable.